(1) Field of the Invention
The present invention relates to an improved process for the preparation of 2-amino-9-(2,3,5-tri-O-benzyl-beta-D-arabinofuranosyl) adenine(V). In particular the present invention relates to a process which uses 2,6-di(trialkylsilylamino)-9-trialkylsilylpurine (II) as a starting compound to produce compound (V).
(2) Prior Art
The compound (V) is used to prepare 9-beta-D-arabinofuranosyl-2-fluoroadenine (VII) or its 5'-phosphate derivative. Compound (V) has been prepared by the use of 2,6-dimethoxyacetamidopurine (A) as a starting material. The procedure involves reacting (A) with a 1-chlorosugar (B) having O-benzyl groups protecting the hydroxyl groups of the sugar. The 2,6-acyl groups are then removed with sodium methoxide and methanol to provide the amino groups in compound (V). The process thus requires relatively vigorous conditions to remove the acetoxy groups and the preparation of the acyl-protected purine is labor intensive. The result is a relatively expensive process.